The table image no longer loads, it's gone down.

Download this. It was recently updated with mod author features.
https://www.nexusmods.com/tabletopsimulator/mods/263?tab=files

You right click a workshop/save file, and do 'check for invalid links'. You can then right click a green invalid link (green means you have the file) and select 'Upload this asset to SteamCloud and replace URL'.

Then after that all you need to do is start up the game and upload the modified file to the workshop.

I believe the image of it is from World of Warcraft, but I have no idea who ripped it/crerated the model.

This is really nice! Where did you get the treasure chest model? I'd like to use it in my campaign and I was wondering whom I should credit.